Re: [問題] 關於PN diode的on/off問題
看板Electronics作者deathcustom (litron-intl)時間14年前 (2011/10/11 10:32)推噓1(1推 0噓 0→)留言1則, 1人參與討論串2/2 (看更多)
: 假設把diode視為constant-voltage model的情形下
: 而且V(d,on)=0.8V。
: 那在這個情況下，兩邊的diode會都是turn-on？
: 還是左邊off，右邊on？
: 我個人是認為是第二種情況，然後算出V=0.4伏特。
: 可是我有幾個朋友覺得是第一種情況？請問這種題目要怎麼下手呢？
: 謝謝大家=)
constant-voltage drop diode:
step 1: assume that each diode has Vd = 0.7V
step 2: if D1 (the left one) is under the on circumstance
then V is equal to 0.7V, and the current from upper source
is equal to 4.3/10k = 0.43mA
step 3: consider that V is equal to 0.7V
the current to the downward shrink will be 5/10k = 0.5mA
step 4: since the shrink I > source I, this case obviously doesn't work,
so D1 is off.
step 5: since D1 is off, the current is (10 - 0.7)/20k = 0.465mA
and V = 5 - 0.465mA*10k = 0.35V
if D1 and D2 have different Vd, we should take that into consideration.
if either D1 or D2 is a ideal diode, both of them are on.
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為什麼那邊那個人那麼傷心呢? ││││││
因為他是北部人啊，吃的比我們還毒哩! 2.5ppm ˍ︵ │││ 還好我們
0.5ppm ◥ ◥ 2ppm ╱ ╱▏ ││ 不用吃…
◤ ◥ ◤ ◥ │￣▏ ˍ 0ppm
| | | ╱ ╱ ﹨
◥◢ ￣ （||） ω ╯ ㄦ
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※ 編輯: deathcustom 來自: 111.81.164.79 (10/11 21:16)
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10/11 21:24, , 1F
10/11 21:24, 1F
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